Primary hepaticobiliary tuberculosis mimicking gall bladder carcinoma with liver invasion: a case report

Primary hepatic tuberculosis is a rare presentation and sporadically reported in the literature, mostly from our part of the world. Sometimes the presentation can be atypical and mimics hepatic tumor and poses diagnostic challenge. We, herein, present a case of a 58-year-old man who presented to us with abdominal pain and weight loss. Raised serum alkaline phosphatase (ALP) and imaging raised a suspicion of gall bladder carcinoma with hepatic invasion. Peroperative frozen section revealed hepatic chronic granulomatous inflammation with caseous necrosis consistent with the diagnosis of hepatic tuberculosis. Surgery was postponed and he was put on antituberculous treatment. It is important to consider tuberculosis in the differential diagnosis of the space occupying lesion of liver in a patient with vague symptoms and abnormal findings on imaging.


Introduction
Tuberculosis (TB) is a worldwide health problem with particularly high prevalence in developing countries [1,2]. The worldwide burden of TB is estimated to be 8.6 million incident cases in year 2012; the South East Asia and western pacific region are among the most prevalent areas accounting for 58% of world TB cases [3].
Abdominal TB is one of the most prevalent forms of extrapulmonary disease [4]. Hepatic involvement occurs in less than 1% of all cases and usually it is associated with foci of infection in the lungs or gastrointestinal tract [5,6]. Primary hepaticobiliary TB is considered very rare among abdominal TB. It is sporadically reported in the literature mostly from our part of the world. It can have atypical presentation and mimic hepatic tumor, posing diagnostic challenge to the clinicians. Herein, we report a case of a middle aged male who presented to our hepatogastroenterology clinic with abdominal pain, vomiting and weight loss and was found to have raised alkaline phosphatase (ALP). The abdominal imaging studies raised a suspicion of gall bladder (GB) carcinoma with hepatic invasion.
However, peroperative frozen section revealed hepatic epithelioid cell granulomata with caseous necrosis consistent with TB.

Patient and observation
A 58-year-old man presented to our hepatogastroenterology clinic with non-colicky pain in right hypochondrium and vomiting for 1 month. The pain was mild in intensity, dull, aching in nature, gradual in onset and progressive in course. It was non-radiating and not associated with meals. There was history of weight loss of 3 kg

Discussion
Hepatic TB as a part of disseminated TB is seen in 50-80% of cases.
However, isolated or primary localized hepatic TB is very uncommon even in countries with high prevalence of the disease. The isolated liver TB without active pulmonary or miliary TB, or other clinical evidence of TB can easily be misdiagnosed in clinical practice, and only few cases have been reported in the literature [7].
Hepatobilliary TB occurs most commonly as a part of miliary tuberculosis due to hematogenous dissemination; however, it may also spread through the lymphatic and portal system. One reason for the rarity of the entity is the unfavorable environment for the growth of mycobacteria in low oxygen tension [8][9][10].
Classically, there are three patterns of hepatic involvement in TB i.e. miliary hepatic, nodular hepatic and biliary tract TB [2]. The first two involve the hepatic parenchyma while the later one involves the biliary tree. The clinical presentation of hepatic TB is most often subtle and insidious. Usually, it presents with nonspecific symptoms including fever and hepatomegaly along with constitutional symptoms such as abdominal pain, anorexia and weight loss.
Page number not for citation purposes 3 Elevated serum levels of ALP and liver enzymes may be observed particularly in biliary TB [8,11,12]. Imaging studies may detect a solitary space occupying lesion in the liver, manifesting as hypoechoic mass on sonography and a hypodense mass with or without hyperdense rim on CT scan [9][10][11][12]. As such, hepatic tuberculoma can mimic hepatocellular carcinoma or hepatoma.
In our case, the patient presented with abdominal pain and weight loss. His ALP was raised. The imaging studies showed distended and irregularly thick walled GB on ultrasound, while contrast enhanced CT revealed thickening of the GB wall at the fundus region with a soft tissue density and reported as GB carcinoma by the radiologist.
The definitive diagnosis of hepatic TB requires pathological and bacteriological evidence. Due to the low yield of culture and acid fast bacilli (AFB) staining, CT/US guided percutaneous biopsy or peroperative biopsy is the preferred approach for the diagnosis.
Diaz et al., reported the sensitivity of mycobacterial antigen PCR up to 57% for hepatic granuloma [5]. In our case, AFB staining of the paraffin embedded hepatic tissue sections was negative but AFB PCR was found positive.
Regarding management of the condition, most often surgical intervention is done due to pre-operative diagnosis of malignancy rather than tuberculosis. As in our case, on the basis of clinicoradiological diagnosis of GB carcinoma, the patient was planned for extended cholecystectomy. Peroperatively, we found multiple whitish spots on the surface of liver, whose frozen section revealed epithelioid granulomata with central necrosis. Two lymph nodes were also sent for histopathology, which revealed reactive changes. The frozen section histopathology spared the patient an unnecessary radical surgery.
Once the diagnosis of hepatic TB is established, conventional ATT for 1 year will cure the disease nearly in 100% of cases. In biliary TB causing obstruction of the biliary tree, there may be a need for ERCP (Endoscopic Retrograde Cholangio-Pancreatography) to relieve the obstruction. Tuberculosis should be kept in the differential diagnosis of space occupying lesions of the liver, especially in endemic areas. Our patient has been given ATT and is on follow up; he was found to be afebrile and had recent weight gain of 4 kg in a period of 4 months of therapy.

Conclusion
Isolated hepaticobililary TB is a rare entity with potentially curable outcome, but presents a diagnostic challenge due to its atypical presentation. It is necessary, to consider it in the differential diagnosis of space occupying lesions of the liver in endemic areas.

Competing interests
The authors declare no competing interests.

Authors' contributions
All authors have read and agreed to the final version of this manuscript and equally contributed to its content and to the management of the case.